Elucidating the role of nanoparticles on photosynthetic biogas upgrading: Influence of biogas type, nanoparticle concentration and light source

Abstract

Three different nanoparticles, namely Fe2O3, carbon coated zero valent iron (CACOI) and SiO2, were added to a mixed microalgae culture in order to improve photosynthetic biogas upgrading. Fe2O3 and CACOI nanoparticles at 10 mg/L supported higher CO2 consumptions compared to their respective controls. The addition of Fe2O3 nanoparticles at 70 mg/L resulted in a 38 % enhanced biomass productivity, and 20 % higher CO2 consumption but delayed exponential growth. The CACOI nanoparticles at 70 mg/L resulted in a shorter lag phase, enhanced CO2 consumption by 13 %, and carbohydrate content enhancement by 64 %, while the addition of SiO2 nanoparticles at this concentration induced an enhanced lipid and carbohydrates production by 47 % and 68 %, respectively. Interestingly, UV light exposure reduced the beneficial effects of nanoparticles, although CACOI nanoparticles still supported a shorter lag phase and higher carbohydrates production at 70 mg/L. In brief, CACOI nanoparticles hold an untapped potential to promote the metabolism of microalgae during photosynthetic biogas upgrading.